[Amps] MOVs
Roger (K8RI)
k8ri at rogerhalstead.com
Fri Jan 24 12:14:37 EST 2014
On 1/24/2014 1:37 AM, Jim Brown wrote:
> On 1/23/2014 10:02 AM, Carl wrote:
>> Inductive industrial equipment use big MOV's for spike suppression on
>> single and 3 phase lines of many voltages.
>
> Again, the problem comes with interconnected equipment when the MOV
> dumps the spike onto ground. Won't repeat previous email. :)
>
We had some 50,000 Joule MOVs "across" a pair of back to back 1200 amp
SCRs. The "chip in those SCRs was no chip. It was a round slice of
Silicon about 1.5 inches in diameter. The gate was easily seen. When
one of those MOVs failed, it was a spectacular ball of fire and Loud.
The MOV were shaped like a trapazoid about 3/4 of an inch thick on a
1/8th inch Aluminum plate. The MOV would vaporize. There were no
particles flying around. The wire connections which were either #6 or
#8 would be pointing straight out as if they had been pulled...hard! The
only thing left was that Al back plate.
I never saw a pair of SCRs survive, so I'm not sure what good they did.
>> I use a pair of large Littlefuse MOV's as a whole house limiter and
>> right at the main panel.
>
> That's an excellent application.
>
>> Lines that are used with electronics when on generator power are also
>> treated with MOV's and .01/2KV buffer rated disc caps.
They would be far more expensive, but wouldn't back to back zener diodes
, or strings of heavily rated zeners be more effective?
I have a bunch of stud mounted zeners in the junk box and it seems like
that'd be a good place for them.
73
Roger (K8RI)
>
> Some things that are common practice are bad practice. Like "The Pin One
> Problem" -- cable shields that go to a circuit board rather than to the
> shielding enclosure. Like power cords whose green wire goes to the
> mounting lug of a terminal strip that is insulated from the chassis by
> paint. I'm sure you can cite plenty more examples. :)
>
> 73, Jim K9YC
>
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com
More information about the Amps
mailing list